When an operation region (a gate width) of a field effect transistor which uses GaAs, SiC, GaN and so on is broadened, output power of devices, such as an inverter circuit, a switching circuit and a radio frequency amplification circuit, can be increased easily.
When a plurality of cells is arranged in parallel, the operation region can be broadened without lowering power gain. In this case, thermal resistance can be reduced by keeping properly intervals between each the cells which are the operation regions.
When a radio-frequency and high-power amplification circuit using an HEMT (High Electron Mobility Transistor) etc. comprises a plurality of cells, it is preferred to arrange the cells so that a loop oscillation may not be produced.